Can only jump once when game starts Unity

Hope you doing well
I just started game dev, in fact, this is my first game.
Yesterday before making my pc sleep my player scripts were working correctly and the character could jump every time I pressed space.
Today I switched on my pc and looked for a way to add stamina to my guy when he drinks coffee, and it works but then I realized that I could only jump once after the game started.
I tried deleting the coffee loot but the problem persists.

I would be greatly appreciated If someone can help, Thank you.

Here is the code

using System.Collections;
using System.Collections.Generic;
using UnityEngine.UI;
using UnityEngine.SceneManagement;
using UnityEngine;

public class Movement : MonoBehaviour
{
Rigidbody2D rb;
float speed = 0.5f;

public float jumpforce = 2.0f;
public Vector3 jump;
public bool isGrounded;
float stamina = 100f;
float maxStamina = 100f;
private Animator myAnimator;
public Slider slider;


// Start is called before the first frame update
void Start()
{
    jump = new Vector3(0f, 2.0f, 0f);
    rb = GetComponent<Rigidbody2D>();
    myAnimator = GetComponent<Animator>();
}

// Update is called once per frame
void Update()
{
     rb.transform.Translate(5f *speed * Time.deltaTime, 0f, 0f);
    Jump();

    slider.value = stamina;

    if (stamina <=maxStamina && speed <= 0.5f) 
    {
        stamina -= 10f * Time.deltaTime;
    }

    if (stamina <= 0) 
    {
        SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);
    }

    if (speed < 0.5f)
    {
        SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);
    }
    //myAnimator.SetBool("isjumping",false);

   
}

void Jump()
{
    if (Input.GetKeyDown(KeyCode.Space)&& isGrounded)
    {
        rb.AddForce(jump*jumpforce,ForceMode2D.Impulse);
        isGrounded = false;
        myAnimator.SetBool("isJumping", true);
    }

    myAnimator.SetBool("isJumping", false);
}

private void OnCollisionEnter2D(Collision2D collision2D)
{
    if (collision2D.gameObject.tag == "Coffe") 
    {
        stamina = stamina + 10f;
    }
}

}

You have it so the jump can only happen when the character is grounded. When the character jumps you are marking them as not grounded, and then you aren’t ever marking them as grounded again. Unless you are setting “isGrounded = true” elsewhere.